De Luca was red-carded for the tackle in the dying moments of his side's 24-7 defeat at the Liberty Stadium on Friday night but has now been hit with an additional suspension that appears to end his season and chances of a Scotland recall.

The statement from the PRO12 disciplinary committee read: "Having considered all of the evidence presented, including the video of the incident, the disciplinary committee considered the incident to be at the top end level for this type of offence, which has a range of suspensions from 12 to 52 weeks and having taken into account aggravating and mitigating factors, decided that a suspension of 13 weeks was appropriate."

The 29-year-old was sidelined for the start of Scotland's Six Nations campaign with a fractured eye socket but was expected to return to the selection mix for their remaining games against Wales and France next month having made a quicker-than-expected recovery. But he is now set to be sidelined until May 27 that will also leave him short of game time to prove his form and fitness ahead of Scotland's summer fixtures with Samoa and South Africa.

Matt Scott and Sean Lamont have formed Scotland's midfield for all three of their Six Nations matches so far with a narrow 12-8 victory over Ireland last weekend keeping their title hopes alive ahead of their next fixture at Murrayfield on March 9.

De Luca, who won the last of his 38 Test caps against Tonga in November, has the right to appeal the ban while Grabham recovered from the tackle to play 80 minutes for Welsh Premiership side Bridgend on Saturday afternoon.